MTFCA Forum

I recently installed a Stromberg LF carb on my speedster. Nice looking, but not only !
The engine starts very well, much better than with NH. Work well, but not enough drive to claim that it outperformed NH.
One issue (well known on these carbs), the float needle does not seal well on its seat. After lapping the needle on its seat, the leakage almost disappear. Almost !
One drop/minute, not much, but not satisfactory.
I have seen that Stan Howe use to make a viton tip on the needle. He was not the only one doing it.
Is there any picture on how to do it ?
I have a steel tip, is it bolted ? Can it be exchanged to a viton one ?

Any other idea ?

I am waiting on this answer also, as I have a very nice OF that I acquired that has a leaking needle. I think everything else is clean. Noel

I just clean up an LF I bought recently. After lapping in the seats, I gave it a light tap with a hammer it seats with no leaks.

Pierre; If that's a picture of your needle, it's way too rough to seal. It needs to be put in a lathe and turned much finer than what I'm seeing. It doesn't look grooved so should clean up with a fine cut and then be polished with 800 paper. You can create a new seat by chucking the existing seat and taking maybe 0.010 or less off the flat face. I also set newly turned needles by carefully centering them in the seat and giving the end a sharp rap with a light hammer (put on a 8-32 nut to protect the threads). If you want to go with a viton tipped needle, I've used viton needles from Holley 4V carb kits, and had a machinist fit the Holley needles to the cut-off Stromberg shaft (press-on fit is fine, and don't try to solder it). Make some measurements before you cut anything to get the overall length close.

Here's a pic of a Stan Howe needle upgrade. These are M series but LF would be similar.
Hope this helps.

Thanks all for the quick answers.

Bruce Compton wrote: ↑

Sat Feb 18, 2023 10:01 pm

Pierre; If that's a picture of your needle, it's way too rough to seal.

Since the picture, I had the tip lapped and the leakage reduced drastically. I will continue, work on the seat, and give the little tap suggested.

Thanks Duane for the picture. If I go the viton tip route, I will certainly make a new needle, as I always try to keep the original somewhere in my garage !